Combined safety switch and limit control



June 13, @9449 e 2/ I & J7 w 4% H. F, ALFERY COMBINED SAFETY SWITCH ANDLIMIT CONTROL Filed June 19, 1941 2 Sheets-Sheet l 62 jrzzxenib r:

fienr ymg er g June 13, 1944; ALFERY I 2,350,978

COMBINED SAFETY SWITCH AND LIMIT CONTROL FilecLJune 19, 1941ZSheets-Sheet 2 trol for opening the circuit "other different abnormalPatented June 13, 1944 2,350,918 COMBINED SAFETY SWITCH AND LIMITCONTROL Henry F. Alfery, Milwaukee, Wis, assignor to Milwaukee GasSpecialty Company, Milwaukee, Wis, a corporation of WisconsinApplication June 19, 1941, Serial No. 398,756

. 8 Claima This invention relates, generally, to protective devices forburner apparatus, and it has partic-:

ular relation to limit control While the particular device which I shalldescribe in connection with the drawings is a coma combined safetyswitch and bined safety switch and limit control operative to cause avalve in the fuel supply pipe leading to the burner to close not onlywhenever a flame to which the device is responsive-as a pilot flame-goesout, but also upon the occurrence of an abnormal temperature, it is tobe understood that the invention, in its broader aspects,

is not limited to this particular use but may be employed in all similarwork as suitable or desired.

Moreover, while I have shown and shall describe the combined safetyswitch and limit control of the present invention in connection with avalve that requires current only for opening the same, the invention isnot limitedto use with valves of this particular type, but may beemployed with valves that require current for both opening and closingthe valve, and it is to be understood that the combined safety switchand limit control may be used for controlling other circuits and otherdevices than the particular circuit and particular device selected forillustration.

One of the main objects of the invention is to provide a combined safetyswitch and limit coninto which the device is connected, for example, notonly upon extinguishment of the flame to which the device is responsive,or upon the occurrence of some While the particular structural featuresand combinations by which I obtain a device of the character set forthare-important features within the more specific aspects of theinvention, it is to be understood that the precise features shown anddescribed may b varied within the broader aspects of the invention.

In order to acquaint those skilled in the art with the construction andoperation of a safety switch embodying the present invention, I will nowdescribe, in connection with the accompanying drawings, one preferredembodiment of the invention.

In the drawings:

Figure 1 is a front view of a combined safety switch and limit controlembodying the present invention, partially in section and with the coverremoved, and showing the switch in closed position; a

Figure 2 is a side elevational viewof the combined safety switch andlimit control;

other abnormal condition or malfunctioning of the apparatus, but'alsoupon the occurrence of an excessive temperature or other additionalabnormal condition or malfunctioning of the apparatus. 1

Another object of the present invention is to provide, in a device ofthe character set forth, a switch or other control device which isadapted to be reset to closed or when the flame to which the device isresponsive is burning and when the temperature has dropped below theexcessive temperature. at which the limit control is operative, or whenthe conditions device is responsive are cured.

Another object of the invention is to provide a combined safety switchand limit control which is of simple, inexpensive, and improved construction em odying few parts and operative cf.

fectively to accomplish the results set forth.

to which the operating position only Figure 3 is a more or lessdiagrammatic view showing the switch in front elevation and inconnection with burner apparatus;

Figure 4 is a fragmentary detail view showing the position of the switchactuator and reset means, with the reset member pressed inwardly to cockor reset the device;

Figure 5 is a view similar to Figure 4 showing the position of theswitch actuator and resetmeans with the switch in open position and thereset member and reset stem released; and

Figure 6 is a detail section taken on the line 8-8 of Figure 4.

In Figure 3 of the drawings, a gas or other fuel burner of any suitableor preferred type is conventionally illustrated at II. The burner in maybe the burner of water'heater, floor furnace, gas range, or any otherburner. A gasor other fuel supply pipe Ii leads to the burner III forthe delivery of gas or other fuel theretofor example, through a mixingchamber (not shown) to which air is admitted in the usual way, as wellunderstood in the art.

A power actuated or electroresponsive valve 9. room or space heater,

the actuator member.

l8 leading'to any suitable source of current or power (not shown). Thevalve actuating means for the valve i2 is connected into the secondarycircuit I9. The safety switch and limit control of the present inventionis also connected into the secondary circuit l9, as will presentlyappear. For purposes of illustration, it may be as-- E sumed that thevalve 12 is of a character to be actuated to open position by closing ofthe circuit l9, and to beheld in open position to supply fuel oroperative energy to the burner It) as long as the circuit is is closed.The valve l2 may have spring means, or other suitable means, foractuating the valve to closed position to shut oil the supply of fuel tothe burner in when the circuit is is opened or otherwise disabled.

The safety switch selected for illustration is similar to that morefully disclosed in the copending application of Harold A. Montz, SerialNo. 394,601, filed May 22, 1941, which became Patent No. 2,340,197 onJanuary 25, 1944, but it is to be understood that the construction andoperation of the safety switch part of the com-'- bined safety switchand limit control of the present invention may, within the broaderaspects of the invention, be of any other suitable orpreferred form.

The safety switch and limit control is shown as located within a housing20. The opposite ends of the back wall of the housing are turned in toform end-walls 2|, and, at the opposite slot 45 through which extends apin 46, the opposite ends of which are secured in the opposite sides ofthe forked inner end of the actuator sides of the back wall, areinturned flanges 22.

The cover 23, which may be of generally U-' shaped cross section, fitsover the inturned end walls 2|, with'the inner marginal edges of thesides of the cover fitting over the flanges 22. Slots 24 openinginwardly from the inner marginal edges of the side walls of the coverfit over the shanks of screws 25 having threaded engagement in the sideflanges 22. These screws 25 are adapted to be tightenedto secure thecover in place on the base of the housing, and to be loosened to permitremoval of the cover. The

screws 25 and slots24 may be positioned at different distances from theopposite ends of the device to assure proper moimting of the.

cover 23.

The front wall of the cover 23 has an opening member 30.

The cam lever 42 has secured thereto, for example, at 48, an overtravelspring arm 49 for actuating the switch to closed position. The lever 42carries a flag or indicator member 50. This indicator member 50 has onand oil markings thereon as shown, or is provided with colored or otherappropriately marked portions for indicating through the opening 26 inthe switch cover 23 the position of the switch, as will presentlyappear.

The means for holding the reset member in the position shown in Figure 1so that the switch will close when the actuator member is releasedfollowing its inward resetting movement and will remain closed as longas the member 40 is held in the position shown in Figure 1 :and theactuator member 30 is in its outwardly projected position is shown inthe form of an electromagnet located within the housing 20. Theelectromagnet'selected for illustration comprises a magnet frame 56-secured, for example, to aterminal bushing 51 in the manner more 1fully disclosed in the copending application of 26, shown in'Flgure 3and in dotted lines in Figures 1, 4, and 5. through which opening .anindicator is adapted to be viewed to indicate the position of theswitch, as will hereinafter appear.

An actuator or reset member 30 operates between open and closedpositions by rectilinear movement through an opening 3| in the adjacentend wall 2! of the housing. The outer end of the actuator member 30 isprovided with an operating button 32. The actuator member 30 is shown ascomprising a pair of actuator member parts forming a fork at the innerend of the actuator member and secured together outwardly of the forkedinner end. A pin 34, secured in the actuator member 30 outwardly of itsforked inner end, cooperates with" the adjacent end wall 2! to limitoutward movement of The actuator member 30 is yieldingly retained in itsoutwardly projected position as shown in Figures 1 and 5, and uponrelease of thebutton' 32, as will presently appear, is returned to thisoutwardly projected position by a coiled return spring 36. This spring36 is shown .as connected between the innerend of the actuator member 34at 31 and a spring anchoring-lug 38 pressed Clarence Wantz, Serial No.328,923, filed April 10, 1940. The coil 58 of the electromagnet is woundaround the legs of the magnet frame 56. The bushing 51 is shown asextending through an opening 59 in the adjacent end wall 2|, and asexternally threaded for threaded engagement at 60 with a nut 62 by meansof which the bushing is clamped in place in the end wall 2| of theswitch housing.

The electromagnet has an armature 64 attached at 65 to the adjacent endor a stem 66, if desired, in a manner to permit self-accommodation ofthe armature when in attracted posi-' tionto the pole ends of the magnetframe 56.

The electromagnet and armature are enclosed within acup 68. The stemextends for reciprocatory movement through an opening 69 in the innerend of the cup 88. The opening 69 is sealed by suitable sealingmaterial, such as a leather washer, felt packing or the like, as in-.dicated at 10, interposed between the inner end of the cup 68 and aspring seating disc 12. The

.end of the stem 68 opposite the end on which the armature 64 is mountedis secured, for example, bya pin 13- to the adjacent end of the resetmember 40. A coiled spring 14 interposed between the spring seating disc12 and a spring seat member I5 actuates the armature 64 to retractedposition and the reset stem and reset -member 40 to the position shownin Figure 5 ass cra the device. 'Ihe'tontact pins II are connected toterminals II. The conductors ll, of the circuit for the valve l2, whichconductors are insulated at 4, enter the housing '2. through aninsulating grommet ll. One of the conductors I9 is connected to theterminal '2 for one switch pin 80, and the other conductor I! isconnected to the other terminal .2 for the other switch Pin 80.

The switch stem 8| has rectilinear sliding movement in the insulatingbase or block oi the switch 18 with the outer end of the stem inposition for cooperation with the free end of the switch operatingspring arm 4. on the cam lever 42. Within the switch block, the reducedinner end of the stem ll passes through a bridging contact plate II. Acoiled spring 92, surrounding the reduced-innerend of the stem 88 andinterposed between the contact plate 0. and an abutment 9! on, orforming a part oi, the switch base, yieldingly urges the plate 9| out ofbridging contact with the contacts OI to open the circuit I. Byengagement of the contact plate 20 with the shoulder 94 on the stem ll,the spring 92 also yieldingly urges the stem II to its outwardlyprojected position as shown in Figure 5. .Stop'means (not shown) may beprovided ior limiting the outward movement of the switch pin ll underthe action of the spring 22.

The pilot burner 25, which is located in juxtaposition to the mainburner ID to maintain a pilot light for lighting the main burner, issupplied with gaseous iuel by a pilot supply pipe 86. The pilot supplypipe 28 may be connected with the main fuel supply pipe ll anterior ofthe valve l2, or it may be supplied with fuel for delivery to the pilotburner in any other desired manner.

Athermocoupie, indicated at 98, is placed in position so that the hotjunction 85 thereof will be heated by the pilot flame as long as thepilot flame is burning. The construction of the thermocouple may besimilar to that more fully disclosed in Oscar J. Leins Patent No.2,126,564, granted August 9, 1938, or a thermopile, or any other form ofthermoelectric generator may be employed.

For the purposes of the present description, suffice it to state thatthe particular thermocouple 98 shown in the drawings comprises an outertubular therrnocouple member and an inner metallic thermocouple memberof different thermoelectric characteristics. The inner thermocouplemember is joined at one end to the outer end of the outer thermocouplemember to form the thermoiunction 89 which is placed in position to beheated by the pilot flame. An inner lead conductor I0 is joined to theinner thermocouple element to form an internal thermojunction, and anouter tubular lead conductor I03 is connected to the outer thermocouplemember-for instance, through a sleeve to form a third thermoiunction.The lead conductors are of flexible character so as to be readily bentto insure neat installations. The inner lead conductor Hill is insulatedfrom the outer'lead conductor i03, for instance, by-a wrapping ofinsulation I04 on the inner lead conductor.

A quick detachable or removable connection is preferably providedbetween .the coil 58 of the electromagnet and the ends of the leads I"and I 03 opposite the ends which are connected to the thermocouple. Thisremovablelead conneo-' tion may be of the formdisclosed in the copendingapplication of Clarencewantz hereinbefore identified,}and is illustratedin that form,

- actuator member ll although it may be of any other suitable orpreferred form. Suillce it to state that the inner lead I" has aconnector cone III which seats in the correspondingly recessed outer endoi the terminal tip I II and is clamped in contact therewith by aconnector sleeve Ill. The adjacent end of the outer tubular leadconductor I" is connected in circuit with one side 0! the coil usthrough the bushing I1, and the other side oi the coil is connected tothe terminal tip I", the parts being suitably insulated as shown.

To start the operation of the system shown in the drawings, as thus fardescribed, the following sequence is followed:

The actuator or reset member 30 is'pressed inwardly'irom the positionshown in Figure 5 by engaging the button 32 with the hand or fingers andimparting pressure thereto. The armature I4 is in released or retractedposition at the beginning of the inward movement of the actuator member3., and the spring 14 holds the pin 43 in engagement with the'lnner endsof the slots 44. As a result, the inward movement of the moves the resetstem 66 with it in the'same direction until the armature 64 is cooked orset into attracted position against the pole ends of the magnet frameIt.

The pilot burner 05 is lighted, or, having been lighted, heats thethermoelectric generator, and

the actuator member 20 is held pressed inwardly until the heat of thepilot flame on the thermoelectric generator has energized theelectromagnet sufllcently so that it will hold the armature 64 attractedthereto.

When the electromagnet is energized suillcient- 1y to hold the armature64 in attracted position, the actuator member 30 is released and thereset stem 66 and reset member 40 remain in cocked position holding thepivot 48 for the cam lever 42 in the position shown in Figure 4. Theswitch operating spring arm 49 assumes the position shown in Figure 4when the actuator member 30 is pressed inwardly. Then with the armatureheld attracted to the magnet frame 58, thereby holding the pivot 48 forthe cam lever 42 in the position shown in Figur 4, when the actuatormember 30 is released the outward movement of the actuator member a,under the action 01' the spring It, causes the pin 46, by its outwardmovement in the cam slot 45, to swing the arm 49 in a counterclockwisedirection (Figures 1 and 4) about the pivot 43 from the positionshown inFigure 4 to'the position shown in Figure 1. The arm 48, by cooperationwith the outer end of the switch pin ll in this movement, moves thecontact plate 9| inwardly against the action of thespring 92 and intobridging contact with the conv character of'thespring arm 4! assuresgood firm eontact'of the-contact plate 92 with the contacts ll, therebeing preferably some overtravel of the cam lever 42 after engagement ofthe contact plate II with the contacts II which tensions the spring arm49 to assume firm and tensioned contact.

If the pilot burner is not lighted to produce the thermoelectric currentfor holding the armature 44 in attracted position upon setting the sameto that position by the actuator member the spring I4 then operates tomove the armature 64 to retracted position. The cam lever 42 movesoutwardly with the movement of the reset stem 66 to released positionthrough the pin connected at 43,and the 'cam slot 45, cooperating withthe pin 46 by this movement of the cam lever 42 relative to the actuatormember 30, swings the arm 49 in a clockwise direction about the pivot 43t the position shown in Figure 5. This releases theswitch pin 88, andthe spring 92 separates the contact plate 90 from the contacts 60. Thisopens or interrupts the circuit l9, and the valve I2 operates to closedposition to shut off the supply of fuel to the main burner.

When the armature is in retracted position with the actuator member 30in released position as shown in Figure 5, the off marking on theindicator arm 50 is positioned to be viewed through the opening 26 inthe cover of the housing to indicate that the switch is off. When thearmature is in attracted position and the releasing the switch pin 86 sothat the switch opens under the action of the spring 92.

When the temperature to which the limit control is responsive dropsbelow the temperature for which the limit control is set, the trippinglever I35 is turned in a clockwise'direction (Figure 1) to position topermit resetting the deactuator member 30 is in its outwardly projectedI surrounds a shaft I26 journaled for turning movement, for example, inthe back wall of the housing 20. One end of the bimetallic element I25is secured at I28 to the outer end of the shaft I25. The other end ofthe bimetallic element is secured to an adjusting lever I30 which ismounted to be turned about the axis of the shaft I26 and relative to theshaft. The

adjusting lever I30 has a pointer I32 which cooperates with thetemperature markings on the dial I34.

The end of the shaft I26 opposite the end which is secured to thebimetallic element I25 extends into the hcusing-26 and carries, fortuming movement therewith, a tripping lever- I35. The cam lever 42 has alaterally extending lug I36 which carries a tripping pin I38 having aroller I39 for cooperation with the tripping lever I35. a When theselected temperature is reached as determined by the setting of thepointer I32 along the temperature markings on the dial I34, thebimetallic element I25 turns the shaft I26 and thereby the arm I in acounterclockwise direction from the position shown, for example, inFigure 1. Assuming that the armature I34 is in attracted position, withthe actuator member 30 in released position and the switch closed asshown in Figure 1, this counterclockwise movement of the tripping leverI35 causes-this lever to engage the roller on the tripping pin I38 andto lift the cam lever 42 upwardly as the device is viewed in Figure. 1.This separates the armature 64 from the magnet frame 56. As

a result, the reset stem moves to retracted posi-- tion and the' arm 49moves to released position vice in the manner already described. As longas the limiting-temperatureor other limitingcondition to which the limitcontrol is responsive continues, however, the tripping lever I35 ispositioned to prevent resetting the device.

The embodiment of the invention shown in the drawings is forillustrative purposes only and it is to be expressly understood thatsaid drawings and the accompanying specification are not to be construedas a definition of the limits or scope of the invention, reference beinghad to the appended claims for that purpose.

I claim: I

1. In a device of the class described, in combination, a reset stem, anactuator member, a cam lever pivoted to said reset-stem, cam means onsaid actuator member for cooperation with said lever, said actuatormember cooperating with said reset stem independently of said cam leverfor resetting said stem to reset position, means for holding said resetstem-in reset position, a controlling member actuated to-operatingposition by swinging movement imparted to said cam lever by cooperationof the cam means on the actuator member therewith upon movement of saidactuator member to released position with said reset stem held in -resetposition, movement of said reset stemto retracted position upon releaseof said holding means swinging said cam lever in a counterdirection bycooperation between said cam lever and the cam means on said actuatormember for movement of said controlling member to safety position, andlimit control means cooperable with said cam lever and operable toseparate said reset stem from said holding means for movement of saidcontrolling member to safety position.

2. In a switch of the class described, in combination, a reset stem, anactuator member, a

cam lever pivotedto said reset stem, cam means on said actuator memberfor. cooperation with said lever, said actuator member cooperating withsaid reset stem independently of said cam lever for resetting said stemto reset position, meansfor holding said reset stem in reset position, aswitch pin having on" and ofi positions and spring-pressed to one ofsaid positions, a spring arm carried by'said cam lever and cooperatingwith said switch pin to actuate said pin to its other position bycooperation of the cam means on the actuator member with said cam leverupon movement of the actuator member to released position with saidreset stem held in reset position, and limit control means cooper-- ablewith one of the parts comprising said reset stem, said actuator member,and said cam lever, and operative to separate said reset stem from saidholding means for movement ofthe switch pin to the position opposite theposition to said pin is spring-pressed. 3. In a switch of the classdescribed, in combi nation, a reset member movable between reseet whichand released positions by rectilinear movement,

her in reset position. a cam lever pivotedto said- 2,850,978 resetmember and having a cam slot therein, a

cam pin carried by said actuator member and engageable in said cam slotfor swinging said cam lever in one direction about its pivotalconnection with said reset member upon movement of the actuator memberto released position with said reset member held in reset position andswinging said cam lever in a counter direction upon movement of saidreset member to released position, a switch operating member movablebetween on and "oil" positions, a spring arm carried by said cam leverand cooperating with said switch operating member to actuate said memberto one of its positions by swinging movement imparted to said cam leverb movement of said actuator member to released position with said resetmember held in reset position and actuated to its other position bymovement of said reset member to released position, and limit controlmeans cooperable with said cam lever and operative to separate saidreset member from said holding means for movement of said switch memberto the position to which it is actuated upon movement oi the resetmember to released position.

4. In a switch of the class described, in combination, a reset membermovable between .reset and released positions by rectilinear movement,

inits second position, movement of said reset member to its firstposition when said actuator member is in its first position causingmovement or said control member to its said first position, anelectromagnet for releasably holding said re set member in its saidsecond position, and limit control means cooperating with said lever forurging said reset member away from said elec-' first position to itssecond position and movement of said actuator member from its secondposition to its first position moves said control member from its firstposition to its second position when an actuator member movable betweenresetting and released positions by rectilinear movement and adapted forresetting said reset member to reset position, means for holding saidreset member in reset position, a cam lever pivoted to said reset memberand having a cam slot therein, a

cam pin carried by said actuator member and engageable in said cam slotfor swinging said cam lever in one direction about its pivotalconnection with said reset member upon movement or the actuator memberto released position with said reset member held in reset position andswinging said cam lever in ,a counterdirection upon movement of saidreset member to released position, a switch operating member movablebetween "on and off': positions, a spring arm carried by said cam leverand cooperating with said switch operating member to actuate said memberto one oij its positions by swinging movement imparted to said cam leverby movement 01' said actuator member to released position with saidreset member held in reset position and actuated to. its otherpositionby movement of said reset member to released position, and limitcontrol means cooperable with said camlever and operative separate saidreset member from said holding means for movement or said switch memberto the position to which it is actuated upon movement of the resetmember to released position.

5. In a combined saiety switch and limitcontroLaswitchconn-oImemberhavingafirstpoaiflon and a second position,an operating lever for said member, raetting means cooperating with saidlever comprising an actuator member yieldingly held in a first positionand movabletherei'romtoasecondpositionandaresetmembermovablei'romafirstpositiontoa'seeondpositionand vice versa and yieldingly urgedtowarditssaidfirstpoeitimmeanawherebymovementoisaidactuatormemberiromitsfirstpositionto its second position moves said resetmemberfromitsfirstpositicntoitssecondposition and movement oi saidactuator member iromitssecondpoeitiontoitsfirstpoeitionmovesstldcmtrolmemberfromitsflrstpoaitimtoits said reset member is held inits second position, movement of said reset memberfrom its said secondposition to its said first position causing movement of said controlmember to its first position, said reset member being yieldingly urgedtoward its said first position, an electromagnet which when energizedholds said reset member second position when said-reset member is held uin its said second positioh, and limit control means cooperating withsaid resetting means for mechanically urging said reset member away fromsaid electromagnet witha i'orce effective for releasing said resetmember from said electromagnet.

'7. In a combined safety switch and limit control, a switch controlmember having a'first position and a second position, resetting meanscomprising a reset member having a reset position and 9. releasedposition and an actuator member movable from afirst position to a secondposition 101' resetting said reset member, means whereby said controlmember is moved into its first position in the movement of said actuatormemberto its second position and in the movement of said reset member toits released position when said actuator member is in its first positionand is also moved to its second position in sition, and limit controlmeans for mechanically urging said reset member away from saidelectromagnet with a force eil'ective for releasing said reset membertherefrom.

8. In a combined safety switch and safety control, a switch controlmember having a first position and a second position, actuating meansfor movin said control member from its said first position to its saidsecond'position, an electromagnet which when energized holds at least aportion of said actuating means in position for seeming and maintainingsaid switch control 4 member in its said second position. and limitcontrol means operative to impart a force to the heldportionorsaidactuatingmeansinadirection away from said electromagnetefiective to releaserromthelattersaidheldportionotsaid actuating means.

HENRY l". ALIIRY.

